# FileHandler

public class **FileHandler** extends [StreamHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html)  
Simple file logging Handler.


The FileHandler can either write to a specified file,
or it can write to a rotating set of files.


For a rotating set of files, as each file reaches a given size
limit, it is closed, rotated out, and a new file opened.
Successively older files are named by adding "0", "1", "2",
etc. into the base filename.


By default buffering is enabled in the IO libraries but each log
record is flushed out when it is complete.


By default the XMLFormatter class is used for formatting.


**Configuration:**
By default each FileHandler is initialized using the following
LogManager configuration properties. If properties are not defined
(or have invalid values) then the specified default values are used.

- java.util.logging.FileHandler.level specifies the default level for the Handler (defaults to Level.ALL).
- java.util.logging.FileHandler.filter specifies the name of a Filter class to use (defaults to no Filter).
- java.util.logging.FileHandler.formatter specifies the name of a Formatter class to use (defaults to java.util.logging.XMLFormatter)
- java.util.logging.FileHandler.encoding the name of the character set encoding to use (defaults to the default platform encoding).
- java.util.logging.FileHandler.limit specifies an approximate maximum amount to write (in bytes) to any one file. If this is zero, then there is no limit. (Defaults to no limit).
- java.util.logging.FileHandler.count specifies how many output files to cycle through (defaults to 1).
- java.util.logging.FileHandler.pattern specifies a pattern for generating the output file name. See below for details. (Defaults to "%h/java%u.log").
- java.util.logging.FileHandler.append specifies whether the FileHandler should append onto any existing files (defaults to false).


A pattern consists of a string that includes the following special
components that will be replaced at runtime:

- "/" the local pathname separator
- "%t" the system temporary directory
- "%h" the value of the "user.home" system property
- "%g" the generation number to distinguish rotated logs
- "%u" a unique number to resolve conflicts
- "%%" translates to a single percent sign "%"

If no "%g" field has been specified and the file count is greater than one, then the generation number will be added to the end of the generated filename, after a dot.


Thus for example a pattern of "%t/java%g.log" with a count of 2
would typically cause log files to be written on Solaris to
/var/tmp/java0.log and /var/tmp/java1.log whereas on Windows 95 they
would be typically written to C:\\TEMP\\java0.log and C:\\TEMP\\java1.log


Generation numbers follow the sequence 0, 1, 2, etc.


Normally the "%u" unique field is set to 0. However, if the FileHandler
tries to open the filename and finds the file is currently in use by
another process it will increment the unique number field and try
again. This will be repeated until FileHandler finds a file name that
is not currently in use. If there is a conflict and no "%u" field has
been specified, it will be added at the end of the filename after a dot.
(This will be after any automatically added generation number.)


Thus if three processes were all trying to log to fred%u.%g.txt then
they might end up using fred0.0.txt, fred1.0.txt, fred2.0.txt as
the first file in their rotating sequences.


Note that the use of unique ids to avoid conflicts is only guaranteed
to work reliably when using a local disk file system.

### Public Constructor Summary

|---|---|
|   | [FileHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#FileHandler())() Construct a default FileHandler. |
|   | [FileHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#FileHandler(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern) Initialize a FileHandler to write to the given filename. |
|   | [FileHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#FileHandler(java.lang.String,%20boolean))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, boolean append) Initialize a FileHandler to write to the given filename, with optional append. |
|   | [FileHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#FileHandler(java.lang.String,%20int,%20int))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, int limit, int count) Initialize a FileHandler to write to a set of files. |
|   | [FileHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#FileHandler(java.lang.String,%20int,%20int,%20boolean))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, int limit, int count, boolean append) Initialize a FileHandler to write to a set of files with optional append. |

### Public Method Summary

|---|---|
| synchronized void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#close())() Close all the files. |
| synchronized void | [publish](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/FileHandler.html#publish(java.util.logging.LogRecord))([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record) Format and publish a LogRecord. |

### Inherited Method Summary

From class [java.util.logging.StreamHandler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html)

|---|---|
| synchronized void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#close())() Close the current output stream. |
| synchronized void | [flush](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#flush())() Flush any buffered messages. |
| boolean | [isLoggable](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#isLoggable(java.util.logging.LogRecord))([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record) Check if this Handler would actually log a given LogRecord. |
| synchronized void | [publish](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#publish(java.util.logging.LogRecord))([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record) Format and publish a LogRecord. |
| synchronized void | [setEncoding](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#setEncoding(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) encoding) Set (or change) the character encoding used by this Handler. |
| synchronized void | [setOutputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/StreamHandler.html#setOutputStream(java.io.OutputStream))([OutputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/OutputStream.html) out) Change the output stream. |

From class [java.util.logging.Handler](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html)

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#close())() Close the Handler and free all associated resources. |
| abstract void | [flush](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#flush())() Flush any buffered output. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [getEncoding](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#getEncoding())() Return the character encoding for this Handler. |
| [ErrorManager](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/ErrorManager.html) | [getErrorManager](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#getErrorManager())() Retrieves the ErrorManager for this Handler. |
| [Filter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Filter.html) | [getFilter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#getFilter())() Get the current Filter for this Handler. |
| [Formatter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Formatter.html) | [getFormatter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#getFormatter())() Return the Formatter for this Handler. |
| [Level](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Level.html) | [getLevel](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#getLevel())() Get the log level specifying which messages will be logged by this Handler. |
| boolean | [isLoggable](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#isLoggable(java.util.logging.LogRecord))([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record) Check if this Handler would actually log a given LogRecord. |
| abstract void | [publish](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#publish(java.util.logging.LogRecord))([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record) Publish a LogRecord. |
| void | [reportError](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#reportError(java.lang.String,%20java.lang.Exception,%20int))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) msg, [Exception](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Exception.html) ex, int code) Protected convenience method to report an error to this Handler's ErrorManager. |
| synchronized void | [setEncoding](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#setEncoding(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) encoding) Set the character encoding used by this Handler. |
| synchronized void | [setErrorManager](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#setErrorManager(java.util.logging.ErrorManager))([ErrorManager](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/ErrorManager.html) em) Define an ErrorManager for this Handler. |
| synchronized void | [setFilter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#setFilter(java.util.logging.Filter))([Filter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Filter.html) newFilter) Set a Filter to control output on this Handler. |
| synchronized void | [setFormatter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#setFormatter(java.util.logging.Formatter))([Formatter](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Formatter.html) newFormatter) Set a Formatter. |
| synchronized void | [setLevel](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Handler.html#setLevel(java.util.logging.Level))([Level](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/Level.html) newLevel) Set the log level specifying which message levels will be logged by this Handler. |

From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. |
| void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. |
| final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\<?\> | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. |
| final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. |

## Public Constructors

#### public
**FileHandler**
()

Construct a default FileHandler. This will be configured
entirely from LogManager properties (or their default values).

<br />

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if there are IO problems opening the files. |
| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control")). |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if pattern property is an empty String. |
|---|---|

#### public
**FileHandler**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern)

Initialize a FileHandler to write to the given filename.


The FileHandler is configured based on LogManager
properties (or their default values) except that the given pattern
argument is used as the filename pattern, the file limit is
set to no limit, and the file count is set to one.


There is no limit on the amount of data that may be written,
so use this with care.

##### Parameters

| pattern | the name of the output file |
|---|---|

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if there are IO problems opening the files. |
| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control"). |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if pattern is an empty string |
|---|---|

#### public
**FileHandler**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, boolean append)

Initialize a FileHandler to write to the given filename,
with optional append.


The FileHandler is configured based on LogManager
properties (or their default values) except that the given pattern
argument is used as the filename pattern, the file limit is
set to no limit, the file count is set to one, and the append
mode is set to the given append argument.


There is no limit on the amount of data that may be written,
so use this with care.

##### Parameters

| pattern | the name of the output file |
| append | specifies append mode |
|---|---|

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if there are IO problems opening the files. |
| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control"). |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if pattern is an empty string |
|---|---|

#### public
**FileHandler**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, int limit, int count)

Initialize a FileHandler to write to a set of files. When
(approximately) the given limit has been written to one file,
another file will be opened. The output will cycle through a set
of count files.


The FileHandler is configured based on LogManager
properties (or their default values) except that the given pattern
argument is used as the filename pattern, the file limit is
set to the limit argument, and the file count is set to the
given count argument.


The count must be at least 1.

##### Parameters

| pattern | the pattern for naming the output file |
| limit | the maximum number of bytes to write to any one file |
| count | the number of files to use |
|---|---|

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if there are IO problems opening the files. |
| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control"). |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if limit \< 0, or count \< 1. |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if pattern is an empty string |
|---|---|

#### public
**FileHandler**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, int limit, int count, boolean append)

Initialize a FileHandler to write to a set of files
with optional append. When (approximately) the given limit has
been written to one file, another file will be opened. The
output will cycle through a set of count files.


The FileHandler is configured based on LogManager
properties (or their default values) except that the given pattern
argument is used as the filename pattern, the file limit is
set to the limit argument, and the file count is set to the
given count argument, and the append mode is set to the given
append argument.


The count must be at least 1.

##### Parameters

| pattern | the pattern for naming the output file |
| limit | the maximum number of bytes to write to any one file |
| count | the number of files to use |
| append | specifies append mode |
|---|---|

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if there are IO problems opening the files. |
| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control"). |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if limit \< 0, or count \< 1. |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if pattern is an empty string |
|---|---|

## Public Methods

#### public synchronized void
**close**
()

Close all the files.

##### Throws

| [SecurityException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/SecurityException.html) | if a security manager exists and if the caller does not have LoggingPermission("control"). |
|---|---|

#### public synchronized void
**publish**
([LogRecord](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/logging/LogRecord.html) record)

Format and publish a LogRecord.

##### Parameters

| record | description of the log event. A null record is silently ignored and is not published |
|---|---|